In many emergency situations it is of great importance to be able to quickly and accurately locate individuals within a large building. For example, in the event of a fire, public safety personnel may need to operate within an unfamiliar building on short notice, in conditions of poor visibility due to smoke or flame. Accurate location information is vital to coordinate rescue operations and ensure the safety of firefighters. Police or military personnel may be faced with similar circumstances, in which accurate and timely location information can help avoid friendly-fire incidents and coordinate action against a criminal or enemy force.
Individuals faced with an emergency involving immediate danger to life or health of themselves or a colleague need to be able to accurately provide their location to emergency/rescue personnel, preferably without human intervention to enable rescue in the case where the individual in need is incapacitated, or all attention must be devoted to his/her protection. In all these circumstances, rapid and automated acquisition of the location of an individual to within a few meters within a large building can be critical in saving lives.
Prior art methods of accomplishing such location do not simultaneously meet the requirements of rapid location determination, automation, and accuracy. Navigation employing conventional maps and visual observation or dead reckoning are not readily automated and thus require time and attention by a human observer. Manual navigation may be vitiated in the case where visibility is impacted by flame or smoke, or where personnel are under hostile fire and unable to establish their location by patient observation.
Enhanced 911, (E911) is a location technology that enables mobile, or cellular phones and other mobile device such personal digital/data assistants (PDAs) to process 911 emergency calls and enable emergency services to locate a physical geographic position of the device and thus the caller. When a person makes a 911 call using a traditional phone with wires, the call is routed to the nearest public safety answering point (PSAP) that then distributes the emergency call to the proper emergency services. The PSAP receives the caller's phone number and the exact location of the phone from which the call was made. Prior to 1996, 911 callers using a mobile phone would have to access their service providers in order to get verification of subscription service before the call was routed to a PSAP. In 1996 the Federal Communications Commission (FCC) ruled that a 911 call must go directly to the PSAP without receiving verification of service from a specific cellular service provider. The call must be handled by any available service carrier even if it is not the cellular phone customer's specific carrier.
The FCC has rolled out E911 in two phases. In 1998, Phase I required that mobile phone carriers identify the originating call's phone number and the location of the signal tower, or cell, accurate to within a mile. In 2001, Phase II required that each mobile phone company doing business in the United States must offer either handset- or network-based location detection capability so that the caller's location is determined by the geographic location of the cellular phone within 100 meter accuracy and not the location of the tower that is transmitting its signal. The FCC refers to this as Automatic Location Identification (ALI).
There are many problems associated with determining a location of device and a caller who needs to place an E911 call in an emergency. On problem is that many E911 calls a misrouted to the wrong PSAP. This can delay the dispatch of emergencies services to the caller. Another problem is that existing mobile technology makes its difficult to accurately locate mobile devices.
Another problem is that triangulation based on time of arrival at multiple mobile-communications base stations (TDOA) has inadequate coverage and is insufficiently accurate unless supplemented by signals provided by local radios placed outside the facility by public safety personnel.
Another problem is that conventional radio-frequency-based location methods do a poor job of providing topological location within a building: that is, location relative to walls, doors, partitions, stairways, and other features whose spatial extent is small but whose significance to a person's ability to move is great.
Another problem is that many mobile devices are not “location-aware.” Location-aware devices are aware of their current geographic location. Mobile telephones and Global Positioning System (“GPS”) devices may be aware of their current geographic location. GPS devices typically determine their current geographic location by communicating with satellites. However, mobile telephones may only determine their current geographic location by communicating with a particular mobile phone interface or telephony switch that provides coverage to a geographic location such as a telephony “cell” but not an exact current geographic location within the cell.
Thus, there exists a critical need for a method of locating individuals making an E911 call that is rapid, automated, accurate, simple and inexpensive to employ, and does not require manual intervention from the person to be located.